1. Field of the Invention
The present invention relates to a vehicle surroundings monitoring apparatus, a vehicle surroundings monitoring method, and a vehicle surroundings monitoring program which monitor the surroundings of a vehicle based on an image taken by a camera mounted on a vehicle.
2. Description of the Related Art
In recent years, there has been known a technology of taking an image of the surroundings of a vehicle with a camera such as a CCD camera mounted thereon, determining an object such as a pedestrian likely to come in contact with the vehicle by detecting the position of the object such as the pedestrian existing around the vehicle based on the taken image, and providing a driver with the information (for example, refer to Japanese Patent Laid-Open No. 2001-6096 (hereinafter, referred to as Patent Document 1)).
In the vehicle surroundings monitoring apparatus in Patent Document 1, a stereoscopic camera consisting of two infrared cameras is mounted on a vehicle and a relative position of an object existing around the vehicle with respect to the vehicle is detected as position data on the basis of a difference (parallax) between images taken by the two infrared cameras. Thereafter, a movement vector of the object relative to the vehicle is calculated based on time series data of the object position and the object likely to come in contact with the vehicle is determined based on the position data and the movement vector of the object.
In this determination, the vehicle surroundings monitoring apparatus sets a close object determination area AR1 corresponding to a road on which the vehicle is traveling and approaching object determination areas AR2 and AR3 located on the outside in the lateral direction of the close object determination area AR1 in a calling attention determination area which is within a predetermined distance in front of the vehicle (corresponding to an area determined according to a relative speed of the object with respect to the vehicle). In the case where the object exists in the close object determination area AR1, the object is a pedestrian or the like on the road and the object is determined to be likely to come in contact with the vehicle. Furthermore, in the case where the object exists in the approaching object determination area AR2 or AR3, the object is a pedestrian or the like on the roadside. Therefore, the approaching object contact determination is made based on the movement vector of the object to determine whether there is a possibility of contact between the object and the vehicle. Thereby, a pedestrian normally walking on the roadside is determined to be unlikely to come in contact with the vehicle, while a pedestrian moving to cross the road from the roadside is determined to be likely to come in contact with the vehicle and appropriate information is provided to the driver.
On the other hand, for example, a pedestrian on the roadside may suddenly run into the road. In that case, it is desirable that the driver is provided with information or vehicle behaviors are controlled as rapidly as possible. In the vehicle surroundings monitoring apparatus in Patent Document 1, however, the possibility of contact between the vehicle and the object existing in the approaching object determination area is determined based on the movement vector calculated from a plurality of time series position data, which requires a long time to determine that the object is likely to come in contact with the vehicle. Therefore, in the case where the pedestrian on the roadside suddenly runs into the road, the apparatus cannot rapidly provide the driver with the information or control the vehicle behaviors disadvantageously.